Heavy duty clutches, generally, and specifically those of the two-plate configuration, are subject to tumbling and torsional activity of their parts at idle speed and torsional activity at higher speeds when the clutch is released. In such arrangements the intermediate plate of the two-plate clutch or the pressure plate of a single-plate clutch have a tendency to tumble at slow speed and a tendency to clatter or vibrate back and forth at high speed as the edges of its drive lugs abut against the opposite edges of the drive lug slots. The first of these motions (tumbling) is caused by gravity. In this movement the lug slots on the intermediate or pressure plate seek support from horizontally opposed pairs of driving lugs, which pair of lugs constantly change in relative position during rotation, imparting a tumbling motion to the intermediate or pressure plate. The second of these motions is caused by a torque loading being imposed on the intermediate plate through a non-uniform rotation of the engine, flywheel, and cover. At the same time the intermediate or pressure plate is attempting, due to inertia, to rotate uniformly. The rotational differences between the intermediate plate and the flywheel creates a torque loading on the intermediate plate. The torque loading can produce a vibratory motion in the intermediate plate that can cause the clutch to clatter.
The unwanted tumbling and vibratory motion cause a "clunking" type noise in the clutch and, additionally, subject the clutch parts to undue wear. Although wearing can be provided for fairly satisfactorily by use of strengthened structural members, recent developments in the engine field now provide much quieter running engines. This improvement in engines has rendered the intermediate or pressure plate torsional and tumbling caused noise an objectionable factor at engine idle conditions.
Although various arrangements for the suppression of tumbling, vibrations and rattling of clutch plates and clutch assemblies have been developed and are known to exist in the prior art, none of the known arrangements provide an extremely simple assembly which requires the use of no special mounting means and, therefore, is capable of utilizing standard clutch parts. Accordingly, it would be desirable to provide a clutch useable with the new engines that has a simply mounted drive means for the intermediate plate which also acts as a vibration suppression unit to reduce the noise generated by the operation of the clutch, and the resulting wear.